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The "scary black box" is a unique item fround in the collapsing archival vein in the Embassy. It is a large steel firearm carry case whose lid is secured with mechanical latches and unnatural metal tendrils[1].
It contains at least one modified M16 (or M4) assault rifle with a short fixed stock, stub pistol grip, and AR-platform barrel guard, along with an unknown number of loaded magazines of unknown caliber, most likely 5.56x45mm NATO as the aforementioned rifles are both chambered in this round.
It is one of two items BSTRD requests before allowing the party into the "pain shelf" room, the other being the 'cool orb thingy'. It is found in the right room of the archival vein, and can be taken after defeating the enemies within. Its contents are wielded by the BSTRD golem during its bossfight.
- ↑ Transcripts:Embassy/Collapse, lines 38-40